688 
PROFESSOR PRES TWICE ON THE ORIGIN 
I take to be due to this moraine detritus, planed down at its lower end by water 
action at the lake period or during the escape of the lake. 
The general character of some other moraine terraces may be seen in pits on the 
side of the road between Spean Bridge and Boy Bridge ; at places N.E. of Boy Bridge; 
near Murlaggan, and elsewhere. The following section of one is on the side of a burn 
(476 feet above the sea), about half a mile west of Murlaggan, where the footpath leads 
across the hills to Bohenie :— 
Fig. 6. 
Section on north side of the Spean "Valley between Achluachrach and Murlaggan. 
a. Coarse gravel formed of reconstructed moraine debris, about 15 feet. 
to. Moraine detritus (Till) of the Spean Valley, about 60 feet. 
In Glen Boy, between Bohuntine and Achavady, the moraine detritus rises on both 
sides of the valley to 200 or 300 feet above the river (there 400 to 500 feet above the 
sea), which has cut its way through it. It consists of a light grey, unstratified sandy 
clay, full of angular fragments and blocks; that it has once been higher is indicated by 
the reconstructed mass of stratified gravel of the same materials overlying it. Before 
its partial denudation it could not have been much, if at all, below the level of the 
lowest of the parallel roads. A like deposit is mentioned by Mr. Milne Home* at 
the entrance of Glen Collarig, forming a cliff 300 to 400 feet high of grey “ boulder 
clay,” rising above the highest “road.” These moraine beds are, I consider, due to the 
meeting and consequent block of the Glen Boy and Glen Collarig glaciers with the 
great mass of ice in Strath Spean, and cannot be looked upon as remnants left after 
denudation of a larger area so much as original local accumulations. (See Map, Plate 46.) 
The large terrace mound of the Turret and the smaller ones lower down Glen Boy 
I look upon in the same way as glacier debris levelled and gravel-covered by subse¬ 
quent water action in connexion with the glacier lakes. This would account, which the 
other theory does not, for the absence of “Deltas” to the upper “Boads.” 
Between Spean Bridge and Fort William is the conspicuous mass of sand and 
* Tz’ans. Roy. Soc. Edinb., vol. xxvii., p. 603. 
